weblogic 多线程用相同的数据库连接导致的错误

   现场做性能测试，第三方厂家报问题，说有锁表的信息，如下图日志。

"[ACTIVE] ExecuteThread: '8' for queue: 'weblogic.kernel.Default (self-tuning)'" - Thread t@3460
   java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:129)
at oracle.net.ns.Packet.receive(Packet.java:293)
at oracle.net.ns.DataPacket.receive(DataPacket.java:104)
at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:315)
at oracle.net.ns.NetInputStream.read(NetInputStream.java:260)
at oracle.net.ns.NetInputStream.read(NetInputStream.java:185)
at oracle.net.ns.NetInputStream.read(NetInputStream.java:102)
at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:124)
at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:80)
at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1136)
at oracle.jdbc.driver.T4CMAREngine.unmarshalSB1(T4CMAREngine.java:1113)
at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:288)
at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:191)
at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:523)
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:207)
at oracle.jdbc.driver.T4CPreparedStatement.executeForRows(T4CPreparedStatement.java:1009)
at oracle.jdbc.driver.OracleStatement.executeMaybeDescribe(OracleStatement.java:1185)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1275)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3576)
at oracle.jdbc.driver.OraclePreparedStatement.executeQuery(OraclePreparedStatement.java:3620)
- locked <6ddfb840> (a oracle.jdbc.driver.T4CConnection)
at oracle.jdbc.driver.OraclePreparedStatementWrapper.executeQuery(OraclePreparedStatementWrapper.java:1491)
at weblogic.jdbc.wrapper.PreparedStatement.executeQuery(PreparedStatement.java:135)
at com.coop.lam.common.dao.BaseDAO.executeQueryByDSName(BaseDAO.java:1449)

       看到日志中的堆栈信息找到业务的方法，发现是一个查询，在Oracle中，查询是不会被堵塞的，那肯定是其他原因。找了一下资料，说是很多线程用到了相同的数据库链接。

        下面来做一个实验重现，每个线程都会用一个链接，如果A线程在使用，B线程就会被堵塞，直到它获得链接为止，所以解决这个问题，要不加大中间件连接池的数量，要不加快业务逻辑处理速度：

import java.sql.Connection;
import java.sql.ResultSet;
import java.util.Properties;

import oracle.jdbc.pool.OracleDataSource;

class slowQuery implements Runnable {
    Thread t;
    
    static Connection conn;
    
    public static void main(String args[]) {
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            OracleDataSource ods = new OracleDataSource();
            ods.setURL("jdbc:oracle:thin:TEST/[email protected]:1521/test");
            Properties prop = new Properties();
            prop.setProperty("MinLimit", "1");
            ods.setConnectionCacheProperties(prop);
            conn = ods.getConnection();
            ods.setConnectionCachingEnabled(true);
            ods.setFastConnectionFailoverEnabled(true);
            for (int i = 1; i < 10; i++) {
                slowQuery r = new slowQuery();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    slowQuery() {
        this.t = new Thread(this);
        t.start();
    }
    
    @Override
    public void run() {
        System.out.println(new java.util.Date());
        try {
            ResultSet rst = conn.createStatement().executeQuery("select slow_query(60) from dual");
            while (rst.next()) {
                System.out.println("test " + rst.getInt(1));
            }
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

create or replace function slow_query(p_secs in number) return number is
begin
  dbms_lock.sleep(p_secs);
  return p_secs;
end;

D:\jdk1.7.13_32\bin>jstack  9304   --需要多运行几次，因为不是没次都能看到问题
2015-10-23 14:37:30
Full thread dump Java HotSpot(TM) Client VM (23.7-b01 mixed mode, sharing):
"DestroyJavaVM" prio=6 tid=0x0008b800 nid=0x2218 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE
"Thread-9" prio=6 tid=0x0510f000 nid=0x2088 runnable [0x05e7e000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(Unknown Source)
        at java.net.SocketInputStream.read(Unknown Source)
        at oracle.net.ns.Packet.receive(Packet.java:282)
        at oracle.net.ns.DataPacket.receive(DataPacket.java:103)
        at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:230)
        at oracle.net.ns.NetInputStream.read(NetInputStream.java:175)
        at oracle.net.ns.NetInputStream.read(NetInputStream.java:100)
        at oracle.net.ns.NetInputStream.read(NetInputStream.java:85)
        at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:122)
        at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:78)
        at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1179)
        at oracle.jdbc.driver.T4CMAREngine.unmarshalSB1(T4CMAREngine.java:1155)
        at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:279)
        at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:186)
        at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:521)
        at oracle.jdbc.driver.T4CStatement.doOall8(T4CStatement.java:194)
        at oracle.jdbc.driver.T4CStatement.executeForDescribe(T4CStatement.java:853)
        at oracle.jdbc.driver.OracleStatement.executeMaybeDescribe(OracleStatement.java:1145)
        at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1267)
        at oracle.jdbc.driver.OracleStatement.executeQuery(OracleStatement.java:1469)
        - locked <0x24c20448> (a oracle.jdbc.driver.T4CConnection)
        at oracle.jdbc.driver.OracleStatementWrapper.executeQuery(OracleStatementWrapper.java:389)
        at com.comtop.test.slowQuery.run(SlowQuery.java:47)
        at java.lang.Thread.run(Unknown Source)

"Thread-8" prio=6 tid=0x0510e800 nid=0x268c waiting for monitor entry [0x05d2f000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at oracle.jdbc.driver.PhysicalConnection.createStatement(PhysicalConnection.java:3169)
        - waiting to lock <0x24c20448> (a oracle.jdbc.driver.T4CConnection)
        at com.comtop.test.slowQuery.run(SlowQuery.java:47)
        at java.lang.Thread.run(Unknown Source)